Simplify the following expression: $\sqrt{160} - \sqrt{40}$
Solution: First, try to factor any perfect squares out of the radicals. $= \sqrt{160} - \sqrt{40}$ $= \sqrt{16 \cdot 10} - \sqrt{4 \cdot 10}$ Separate the radicals and simplify. $= \sqrt{16} \cdot \sqrt{10} - \sqrt{4} \cdot \sqrt{10}$ $= 4\sqrt{10} - 2\sqrt{10}$ Finally, simplify by combining the terms. $= ( 4 - 2 )\sqrt{10} = 2\sqrt{10}$